1. Field of the Invention
The present invention relates to steering systems for marine vessels and, more particularly, to automatic steering systems for such vessels.
2. Description of the Prior Art known in the art. Such systems comprise means for setting a desired course. The actual heading of the vessel is constantly compared with the desired heading so as to develop a finite heading error signal whenever the vessel deviates from the desired course. The heading error signal is used to correct the rudder position so as to bring the vessel back to the desired heading.
In order to operate in an efficient and practical manner, present day autopilots include manual controls to optimize performance for varying wind and sea conditions as well as changing ship speeds. However, with such manual adjustment, the operator is frequently unable to realize optimum conditions since the time constants on a large vessel are fairly long. With such vessels, it may be necessary to run for periods of ten minutes or so before the operator can determine the effect of a manual adjustment. The adjustments therefore become a matter of trial and error with a consequent loss in operating efficiency and increase in fuel consumption.
The circuit of the present invention utilizes sensors which detect slight changes in heading error, rudder angle and speed which would be too small to be detected by an operator and uses these signals to compute the optimum gain and amount of rudder offset.